This SBlR-AT Phase I project will evaluate the safety, mechanism of action, and clinical effects of recombinant ovine Interferon tau (rolFN-tau) in patients with multiple sclerosis (MS). IFN-tau is a Type 1 interferon that possesses biological activity, including anti-inflammatory effects, similar to that of other Type 1interferons, lFN-alpha and IFN-beta. However, in contrast to IFN-alpha and IFN-beta, lFN-tau is orally bioactive. When administered orally, IFN-tau induces IL-10 and reduces lFN-gamma in rodents and humans, and prevents the symptoms and signs of experimental allergic encephalomyelitis (EAE), an animal model of MS. Moreover, based on the results of Phase I clinical trials, lFN-tau appears to be extremely well tolerated and causes fewer side effects than injected lFN-alpha or IFN-beta. In the proposed project, the effects of a single daily oral dose of rolFN-tau will be evaluated in twenty patients with relapsing-remitting MS in a nine-month clinical trial. Safety and tolerability will be carefully monitored, while the effects of IFN-tau on T cell-mediated immunity will be determined by measuring the levels of Th1 and Th2 cytokines in serum and in white blood ceils (WBC) from whole blood from before, during, and after treatment. Assessment of disease progression will be based on serial monthly determinations of the number of gadolinium-enhanced plaques by MRI. The results of this trial should allow us to determine the safety and therapeutic potential of lFN-tau in MS and provide the basis for designing a larger, longer controlled clinical trial [unreadable] [unreadable]